Google keeps a history of anyone that you have contacted in the past. Where this becomes an issue for you is if someone has left the company or their information has changed.
- You may see old contacts when composing an email
- Navigate to Other Google Contacts
- Either search for the contact or find the contact in the list of Other Contacts
- Select the three dots on the top right corner and select Delete
- Alternatively you can select on the Pencil icon to edit the contact.